1. Field of the Invention
The present invention relates to a container packaging apparatus, and in particular to a container packaging apparatus for packaging a container, for example, a wafer case containing a plurality of semiconductor wafers therein, so as to be packed in a packaging bag, such as a plastic bag.
2. Description of the Related Art
In order to prevent any damage or contamination during being transported, semiconductor wafers, such as silicon wafers, which have been manufactured in a wafer manufacturing plant are typically loaded into a wafer cassette, an intermediate holder, made of synthetic resin, which is in turn packed in a wafer case whose cover can be closed tightly via a gasket (a packing member). The wafer case is further packed firstly in an inner bag made of nylon (the trade name of polyamide fiber) and then in an outer bag made of aluminum, in which the wafer case may be enclosed in respective bags via heat sealing. This provides a packaging structure that can prevent any external fine dust or the like from entering into the wafer case to form a deposit on the wafer surface during the transporting operation.
To carry out manually the packaging procedure as described above, firstly the container is inserted into the packaging bag, and then the packaging bag in its sealing area is set in a heat sealing machine or a pressure sealing machine which may carry out the sealing operation with or without deaeration. Subsequently, an opening region and a rear end portion located opposite to the opening region of the packaging bag are folded manually, and both of the end portions of the packaging bag are fixed securely with tape attached thereon, respectively.
If all of the above steps are carried out manually, it takes a considerably long time to accomplish the packaging procedure and adversely it tends to develop crimps in the sealed area. In addition, when carrying out the packaging process incorporated with the deaeration effective in the bag, the condition after the deaeration varies widely, inhibiting the stable packaging procedure to be accomplished. Further disadvantageously, the process of folding and fixing the end portions of the packaging bag by attaching the tape has also imposed a lot of troubles.
There is one known apparatus to address the above problem, including a container packaging apparatus as disclosed in the cited reference, Patent Document No. 1, for example. The container packaging apparatus disclosed by the cited Patent document No. 1 allows for the packaging procedure to be carried out by the divided steps, where the container packaging apparatus comprises: a packaging bag supply means for supplying a transverse-mounted packaging bag into a predetermined position; a container loader means for supplying a container to be packed into a predetermined position; a container insertion means operable to hold by vacuum chuck an opening region of a packaging bag with the aid of a pair of vertically arranged suction arms so as to open the packaging bag in the site of the opening region by moving each of the pair of suction arms vertically away from each other and subsequently to insert the container into the packaging bag through the opening of the bag; a shaping means operable to deaerate the packaging bag containing the container packed therein by a suction nozzle and subsequently to make a seal for closing the opening; and a packaging bag end portion processing means operable to fold an end portion of the sealed packaging bag and fix the folded end portion of the packaging bag (by attaching the tape).
According to the cited Patent Document No. 1, in the packaging process for carrying out the steps including: inserting the container into the packaging bag; deaeration and packing of the container; heat sealing in the opening of the packaging bag; folding the end portion of the packaging bag; and attaching the tape (label), the packaging apparatus can make the packages uniform in their quality, even if containers different in size, shape or the like are mixedly transferred through respective steps, so as to facilitate mechanization and automation of respective processes and thereby improve a throughput in the packaging procedure.
[Patent Document No. 1]
Japanese Patent Laid-open Publication No. 2002-154505 However, in the cited Patent Document No. 1, during the container being inserted into the packaging bag as described above, the pair of suction arms holding by vacuum chuck the upper and the lower sides of the packaging bag in its opening region are moved vertically so as to open the bag in the site of the opening region yet without fixing the rear end portion of the packaging bag mounted transversely. The apparatus of the cited Patent Document No. 1 has many drawbacks in association with this configuration.
Specifically, in case of the packaging bag that is mounted transversely (i.e., the longitudinal direction of the bag extends approximately horizontally) and whose rear end portion is not fixed, the degree of freedom of positioning in the rest part of the packaging bag excluding the opening region is relatively higher than that in the packaging bag mounted longitudinally (i.e., the longitudinal direction of the bag extends approximately vertically). This could make it difficult for the shape of the packaging bag (the shape of the inside space of the bag) in its open configuration to be stabilized. Consequently, it would not be possible to insert the container into the bag in a smooth manner and also the crimps are more apt to occur in the packaging bag.
Besides, when the container is being inserted into the bag, specifically the bag that is mounted vertically, the container with the assistance of its own weight is more smoothly handled into position substantially at a limited location in the bottom of the packaging bag. This has contributed to fewer crimps developed in the packaging bag after the container having been placed therein. Further advantageously, in the bag mounted vertically, a pair of ear portions each having a triangular shape (hereinafter referred to as a triangular ear portion) emerging in both sides of the rear end portion (similarly in the front end portion) of the packaging bag upon insertion of the container could be substantially stable in size and shape.
In contrast to this, in the packaging bag mounted transversely, it has been difficult for the container to be packed in position substantially at a central location (i.e., the substantially limited location), in the bottom of the packaging bag. This tends to produce more crimps appearing in the packaging bag and the left and the right triangular ear portions of the rear end portion of the packaging bag emerging unevenly in its size and shape after the container having been inserted into the packaging bag. Consequently, when each of the triangular ear portions in the front end portion and the rear end portion of the packaging bag is folded and fixed with the tape in both sides with respect to the container, the triangular ear portions defined in either side with respect to the container could not be long enough to be fixed well, and thus the packaging of the container with a resultant high level of quality and the stability during the procedure could not be obtained.
In addition, the process for opening the packaging bag mounted transversely has been accomplished simply by moving each of the pair of suction arms holding by vacuum chuck the region of the opening of the bag in the up or the down directions. Consequently, in many cases, the resultant extension of open area of the bag could be insufficient relative to the size of the container. As a result, the packing of the container in the bag could have a trouble, leading to the failure in carrying out the packing procedure efficiently.
In the light of the above circumstances, the inventors of the present invention have made an enthusiastic research and accomplished the present invention based on their finding from the research that if the rear end portion of the transversely-mounted packaging bag is fixed when the container is inserted into the packaging bag, the degree of freedom of positioning can be reduced in the rest part of the packaging bag excluding the opening region when the packaging bag is opened, and thus the container can be handled smoothly into position, or the substantially limited location, at any times, which can help reduce the occurrence of crimps in the packaging bag after the insertion of the container even in the case of the transversely-mounted packaging bag having been employed, while providing the uniformity in size and shape between the left and the right triangular ear portions in the rear end portion of the packaging bag, thereby allowing to provide the packaging of the container with the resultant high level of quality in the stable manner.
The inventors of the present invention have accomplished the present invention further based on the finding from their research that if a plurality of opening expansion members are inserted in the bag previous to placing the container thereinto, which members are then moved radially in different directions from an approximately central location of the opening taken as the center so as to expand the open area of the opening from inside thereof, then the sufficiently large open area relative to the size of the container can be ensured in the opening of the bag.